Uterine Leiomyosarcoma and Other Smooth Muscle Tumors of the Uterus

Uterine leiomyosarcoma (LMS) is a rare form of cancer of the uterus, where smooth muscle tumors develop in the lining of the uterus. However, the generic term smooth muscle tumor is used to describe both cancerous and non-cancerous tumors of the uterus. Uterine leiomyosarcoma refers to malignant tumors, whereas an example of a benign tumor is a fibroid, also known as uterine myoma (short for leiomyoma).The uterus is the most common site for the development of both cancerous and non-cancerous smooth muscle tumors.

Uterine Leiomyosarcoma PrognosisUterine leiomyosarcoma is an extremely uncommon cancer that affects as few as seven adult women in a million. The five-year survival rates for women who are diagnosed in Stage I of the disease is around 50 to 65 percent. If the disease is more advanced at the time of diagnosis, the five-year survival rate for uterine leiomyosarcoma drops to zero to twenty percent. The poor prognosis is largely due to two factors: the high incidence of recurrence and the ease with which the disease can spread to other organs of the body through the blood and lymphatic systems.

Benign Smooth Muscle Tumors of the UterusUnlike uterine leiomyosarcoma, which is a rare form of smooth muscle cancer, uterine fibroid are a widespread, non-malignant condition that affects more than thirty percent of women in the Western World. Most fibroids, however, are asymptomatic and require no treatment.

A Common Misconception About the Uterus. In the vast majority of cases, non-cancerous smooth muscle leiomyomas (fibroids) of the uterus do not lead to the development of uterine leiomyosarcoma. Progression to cancerous uterine leiomyosarcoma, from benign smooth muscle leiomyomas, is extremely rare. Fibroids are only removed if they cause problems or impair fertility, not because there is a risk of cancer. Even a woman with a severe case of fibroids is at no greater risk of developing uterine leiomyosarcoma.

Uterine Leiomyosarcoma and Endometrial Adenocarcinoma:Uterine leiomyosarcoma is sometimes confused with the most common type of uterine cancer, called endometrial adenocarcinoma, because both cancers originate within the uterus. The main difference between the two types of cancer is the type of uterine tissue affected. Leiomyosarcoma occurs in the smooth muscle of the uterus called the myometrium, while endometrial adenocarcinoma develops in the lining of the uterus (the endometrium).